I hope we can have him available fairly quickly but obviously not Saturday.Pep Clotet.
The on-loan winger has not figured since limping off during Blues’ 2-1 home win against Stoke City at the end of August.
"He has started to train with the team this week," said Clotet.
"He is working a lot on his fitness as well because he was working on getting over his injury, so I hope we can have him available fairly quickly but obviously not Saturday."
Montero has been doing a lot of solo drills with the physios and sports science staff and this is the first time he has joined in with the main group.
Meanwhile, goalkeeper David Stockdale is to undergo a scan after injuring his hand during a training session.
"Stocky is having a scan today on this problem in the hand but I don't think it is going to be a long one," said the Blues boss.
Stockdale also hyper-extended his elbow blocking a shot in training last week and inflammation meant he was unable to take his place on the substitutes' bench for the visit of Luton Town.
Long-term absentee Maikel Kieftenbeld is continuing to make progress with his return to fitness following knee surgery.
"From the reports that I have we are expecting him to try to join us in training for January or February," added Clotet.
"We are not putting much pressure on it because every knee is different, but I do know he is doing very well in his recovery and probably the timing will be around that.
"Normally it's around six to eight months to be on the grass so he is going to hit that because he is a very good pro and he has done everything by the book with his knee. He is on the right track."
The only other Blues played sidelined through injury is midfielder Gary Gardner who will be unavailable for several weeks with a knee problem which he sustained against Leeds United.